The present invention is directed to a braking system of a vehicle, comprising braking actuators supplied by two different sources of energy. In particular, the braking actuators hereby described may be supplied by one or more of pressurized air and electrical power. The braking system of the present invention further comprises two separate electronic control units (ECU) which allow optimizing the source of braking energy according to the running conditions of the vehicle, and more particularly, under degraded running conditions.
Pneumatic brake actuators are commonly used on industrial vehicles. For safety purpose, backup pneumatic systems and several recipients of pressurized air are necessary, which increase the global weight of the braking system. In addition, in case of failure or air leakage, the backup systems do not always allow to brake all the wheels of the vehicle. Thus, an emergency braking action may lack control.
Hybrid brake actuators are known, also called bi-energy brake actuators, which can be activated by two different sources of energy. This kind of brake actuators are for example described in WO03014588 and WO2008030204. A method of activating these brake actuators is in addition described in the patent application PCT/EP2014/001813. However, although the electrical management of the brakes may compensate some failure of the pneumatic system, the pneumatic backup system still remains in the currently used systems.
It is desirable to provide an improved brake arrangement. In particular, it is desirable to replace the pneumatic backup elements, partly or completely, by electrical elements, which allow a safe braking in case of degraded conditions. It is also desirable to optimize the size of the pneumatic system, in order to limit the weight and the overall energy consumption of the vehicle.
The braking system of the present invention comprises an electrical power supply unit, a compressed air supply unit, at least one bi-energy brake actuator, which can be activated by any one of an electrical power supply unit and a compressed air supply unit or by both, simultaneously. The braking system further comprises a first and a second electronic control unit (ECU) both supplied by the electrical power supply unit. The first ECU is connected to, and provides power to the electrical actuator of the bi-energy brake actuators. It is further connected to the electrical parking brake hand control, the brake pedal sensor module, and to one or more wheel sensors. It may further be connected to a trailer control module (TCM).
The second ECU is connected to one or more brake system modules (EBS), and the brake pedal sensor module. It controls the pneumatic activation of the bi-energy brake actuators. The second ECU controls and provides electrical power to the electronic brake system module (EBS), the brake pedal module, and optionally to the air production module (APM).
The electrical power supply unit comprises two distinct sources of electrical energy. It is electrically connected to both the first ECU and the second ECU.
The compressed air supply unit comprises an air reservoir, preferably a single air reservoir dedicated to all the brake actuators of the vehicle, including the bi-energy brake actuators. In particular, the air reservoir is connected to the front and the rear axles of the vehicle, and optionally to additional axles. The air reservoir may further be connected to pneumatic or hybrid brake actuators of a trailer or a semi-trailer. The air reservoir, or air tank, is fed with compressed air by the mean of a compressor. The compressed air supply unit may further comprise air cleaner, air desiccator, and/or any other device able to purify the air. The compressed air supply unit optionally comprises a trailer control module (TCM). The compressed air supply unit may further be connected to one or more electronic brake system module (EBS), which can be either single or double.
Some brake system elements may be connected to a high speed data bus. In particular, one or more of the power supply unit, the first and the second ECUs, the electronic brake system modules (EBS), and the trailer control module, can be connected to a vehicle data bus, which may further be connected to other sensors, such as a continuous clutch pedal sensor, one or more door switch sensors, or an accelerator pedal sensor.
Further, the first and the second ECUs are directly connected to each other through a dedicated circuit. Such a direct connection improves the management of a concomitant activation of the brake actuators with the electrical power and the pneumatic energy.
The present braking arrangement preferably comprises two bi-energy actuators, positioned on two wheels of a same axle. In an advantageous configuration, a rear axle is provided with a pair of bi-energy brake actuators, and the other axles are equipped with traditional pneumatic brake actuators. However, any other configurations are possible, including the one where all the wheels of the vehicle are equipped with a bi-energy brake actuator.
The present invention also encompasses a method of managing the bi-energy brake actuators in case of failure of the service brake system, either with the pneumatic circuit or the electrical circuit.
The invention also comprises a vehicle equipped with the braking system hereby described.
In FIGS. 3, 4, 5, 6, 7, and 8, the connections which are represented by plain lines correspond to fluidic connections, and in particular to pneumatic connections. The connections represented by dotted lines correspond to electrical connections. Such electrical connections indicate the transmission of electrical power or information, or both.